1. Field of the Invention
The invention relates to an inert gas ion laser comprising a member having an elongated, gas-filled cylindrical discharge channel, two electrodes with which a gas discharge can be generated in the discharge channel and two spaced mirrors forming an optical resonator which enclose the discharge channel between them.
2. Description of the Prior Art
For years, the need for coherent light sources which should emit a continuous beam in the visible spectrum with a power between 0.5 mW and 5 mW has been covered by helium-neon lasers.
In the meantime, this type of laser has been developed into a technologically mature component with long-term stability which can also be inegrated without further ado into the most modern optical systems, for example video disc players. There unsatisfactory, however, is the fact that HeNe lasers continue to require a great deal of space. Thus, the currently smallest tube, the 0.5 mW laser offered by the Spectra-Physics Company under the designation "007", still has a length of 11.5 cm and a diameter of about 2.5 cm and further advances in this area are hardly possible for physical reasons.
Alternatives had therefore already been sought. The argo laser thereby had to appear particularly attractive: it offers amplification values per length unit that are an order of magnitude higher than in HeNe lasers. Over and above this, calculations on the basis of balance equations with which the laser intensification mechanisms and the gas discharge events can be approximately described has led to similarity laws which at least did not exclude a start-up even given very narrow, short discharge tubes (periodical Physik 215 (1968) 437 and 219 (1969) 5). Insofar as known, these scaling rules were not, however, verified for tube diameters &lt;1 mm; efforts, instead, were exclusively concentrated on larger discharge volumes for generating medium through high output powers. Mini argon lasers may possibly not have been taken into consideration because technological problems were envisioned (cf., in this regard, U.S. Pat. No. 3,646,476, initially cited patent, particularly Col. 3, paragraph 2) or excessively high magnetic fields were considered necessary (cf., in this regard, Appl. Phys. 4 (1974) 141, particularly Eq. ( 7)).
Semiconductor lasers which are extremely compact and are already used where a light wavelength &gt;0.7 .mu.m is acceptable and excessively high demands are not made of the reliability may possibly present serious competition. It is therefore presently entirely unresolved as to whether and, under given conditions, when laser diodes are in a position to penetrate into high-frequency areas as well.